Bruise, or CONTUSION, signifies an injury inflicted by a blow or sudden pressure, in which the skin is not wounded, and no bone is broken or dislocated. Both terms, and especially the latter, are employed in surgery to include all such injuries in their widest range, from a black eye to a thoroughly crushed mass of muscle. In the slighter forms of this injury, as in ordinary simple bruises, there is no tearing, but only a concussion of the textures, the utmost damage done being the rupture of a few small blood-vessels, which occasions the discoloration that is always observed in these cases. In more severe contusions, the subjacent structures—muscles, connective tissue, vessels, &c.—are more or less ruptured, and in extreme cases, are thoroughly crushed, and usually become gangrenous. The quantity of blood that is extravasated mainly depends upon the size and number of the ruptured blood-vessels, but partly also on the nature of the textures of the injured part. Thus, a lax tissue, as that of the eyelids, favours the escape of blood into the surrounding parts. Moreover, the constitution of the patient has some influence, and many persons, especially, according to Paget, pallid, fatty, soft-skinned women, though suffering from no apparent disease, as well as those affected with scurvy or with the 'hemorrhagic diathesis' (see HÆMOPHILIA), are subject to extravasations, and consequently to discolorations, very disproportionate to the injuries that cause them.
The most characteristic signs of a recent contusion are more or less Shock (q.v.), pain, swelling, and discoloration of the surface from effused blood (commonly known as Ecchymosis, q.v.). There is nothing special in the character of the shock, but it is worthy of notice that it is most severely felt in injuries of special parts—as the testes, the breasts, and the larger joints, which are often followed by remarkable general depression, faintness, loss of muscular power, and nausea. The immediate pain following the blow is succeeded by a feeling of numbness, which, after a varying time, unless the part is killed, gives place to a heavy, aching pain. Although some depression may usually be observed immediately after the infliction of the blow, swelling of the parts rapidly follows, as may be well seen when a child receives a blow on the head, or in the wale that rises after the lash of a whip. In lax parts, such as the eyelids, the swelling is often considerable, and may remain for a week or more; but in other parts it usually subsides in two or three days. The discoloration of the skin consequent on blows is of a more or less purple tint, varying from black to crimson or pink. 'Blackness,' says Paget, 'usually indicating intense injury, is probably due to the extravasation of a large proportion of entire blood; crimson or pink tints, to the prevalence of a blood-stained fluid; blue, to the degrees in which blackness is veiled by the cuticle and skin, as the colour of blood in veins is; and perhaps some of the shades of pink to the partial aeration of the blood by the penetration of air through the epidermis. After a variable time, proportionate to the severity of the injury, these colours fade out, passing most commonly through gradually lightening shades of brownish olive, green, and yellow.' The causes of these changes of colour are not clearly known; as, however, the changes are not observed in bruises of parts removed from air and light, they are probably due to oxidation and actinic agency. When a severe bruise tends to a natural cure, and there is no inflammation or sloughing, the effused blood is generally absorbed, the liquid portion rapidly disappearing, while the blood-cells are more slowly removed. In some cases, it is possible that the effused blood may become organised into vascular connective tissue, which takes part in the repair of the injured tissue. We need not follow the course of a bruise in which active inflammation with suppuration ensues, or in which sloughing takes place, as these complications must be treated according to the ordinary rules for those affections. There are, however, one or two ill consequences following partial recovery, which require notice. Thus, in some organs, as the breast, abscess may ensue long after a blow; or a sensitive indurated lump may remain; or (more commonly) there may be long-continued pain, without change of texture; or, lastly, cancer may ensue. Blows on superficial bones, as those on the skull, are not unfrequently followed by very painful thickening of the periosteum; a muscle violently struck may be paralysed, and rapidly waste away; and constitutional diseases, such as gout and rheumatism, are well known to localise themselves with special severity in parts that have once been seriously bruised.
With regard to treatment, simple and not very severe bruises require little treatment but the rest necessary for the avoidance of pain; but the removal of the swelling and discoloration may be hastened by the application of various local stimulants, which seem to act by accelerating the circulation through the bruised part, and promoting the absorption of the effused fluid. Friar's balsam, compound soap liniment, or poultices made with the roots of black bryony beaten to a pulp, are popular remedies of this class. Tincture of arnica has a great reputation; but experiments have made it very doubtful whether it is any more efficacious than simple spirit of the same strength. A solution of sulphurous acid, and hazeline and other preparations of the American Witch-hazel (q.v.), are of more value. They should be kept constantly applied to the bruised part on lint or cotton-wool. Pugilists, who are probably better acquainted with ordinary bruises than any other class of men, are in the habit of removing the swelling of the eyelids that often naturally occurs during a prize-fight to such an extent as to close the eyes, by at once puncturing the eyelids at several points with a lancet; and their favourite remedy for a black eye or other bruise on the face is a fresh beefsteak applied locally as a poultice. Bruises of a more severe nature, as when there is much breaking or crushing of the tissues, must, of course, at once be placed in the hands of a surgeon. See Sir James Paget on 'Contusions' in Holmes's System of Surgery.